1. Field of the Invention
The present invention relates generally to a multi-band antenna, and more particularly to a multi-band antenna used for electronic devices, such as notebook.
2. Description of the Prior Art
As communication technology is increasingly improved, the weight, volume, cost, performance, and complexity of a communication system also become more important, so antennas that transmit and receive signals in a wireless communication system especially ‘draw designers’ attention. In a wireless local area network (WLAN), because the space for setting up an antenna is limited and the antenna should transmit a large amount of data, the antenna should be carefully designed. And for the requirement of small size, the antenna is needed to be able to transmit all signals of WLAN bands, 802.11b(2.4 GHz) and 802.11a(5.2 GHz).
Referring now to FIG. 1, a conventional multi-band antenna 1′ is shown and includes a first antenna 100′ and a second antenna 200′ having similar structure as that of the first antenna 100′. Both of the first antenna 100′ and the second antenna 200′ are used as WLAN antennas. The second antenna 200′ has an L-shape low-frequency radiating portion with a band portion 4′ located on the free end thereof, so that the low-frequency radiating portion of the first antenna 100′ and the low-frequency radiating portion of the second antenna 200′ respectively locate in different planes. This structure reduces the interference between the first antenna 100′ and the second antenna 200′. However, with the volume of the antenna reducing, the disturb therebetween will become greater, and this structure can not make the antenna 1′ achieve enough bandwidth.
Hence, an improved antenna is desired to overcome the above-mentioned shortcomings of the existing antennas.